Identification and susceptibility testing of microorganism by direct inoculation from positive blood culture bottles by combining MALDI-TOF and Vitek-2 Compact is rapid and effective.

Abstract

OBJECTIVES:

The objective of this study was to evaluate the reliability and accuracy of the combined use of MALDI-TOF MS bacterial identification and the Vitek-2 Compact antimicrobial susceptibility testing (AST) directly from positive blood cultures.

METHODS:

Direct identification by MALDI-TOF MS and AST were performed in parallel to the standard methods in all positively flagged blood cultures bottles during the study period.

RESULTS:

Three hundred and twenty four monomicrobial positive blood cultures were included in the present study, with 257 Gram-negative and 67 Gram-positive isolates. MALDI-TOF MS identification directly from blood bottles reported the correct identification for Enterobacteriaceae in 97.7%, non-fermentative Gram-negative bacilli 75.0%, Staphylococcus aureus 75.8%, coagulase negative staphylococci 63.3% and enterococci 63.3%. A total 6156 isolate/antimicrobial agent combinations were tested. Enterobacteriaceae group and non-fermentative Gram-negative Bacilli showed an agreement of 96.67% and 92.30%, respectively, for the Gram-positive cocci the overall agreement found was 97.84%.

CONCLUSIONS:

We conclude that direct identification by MALDI-TOF and inoculation of Vitek-2 Compact AST with positive blood culture bottles yielded very good results and decreased time between initial inoculation of blood culture media and determination of the antibiotic susceptibility for Gram-negative rods and Gram-positive cocci causing bacteremia.

• Authors: María-Pilar Romero-Gómez, Rosa Gómez-Gil, Jose Ramón Paño-Pardo, Jesús Mingorance
• Journal: The Journal of infection (J Infect) Vol. 65 Issue 6 Pg. 513-20 (Dec 2012) ISSN: 1532-2742 [Electronic] England
• PMID: 22940580 (Publication Type: Journal Article)
• Copyright: Copyright © 2012 The British Infection Association. Published by Elsevier Ltd. All rights reserved.

Chemical References

• Anti-Bacterial Agents

Topics

• Anti-Bacterial Agents (pharmacology)
• Bacteremia (blood, microbiology)
• Bacterial Typing Techniques (methods)
• Gram-Negative Bacteria (chemistry, classification, drug effects, isolation & purification)
• Gram-Positive Bacteria (chemistry, classification, drug effects, isolation & purification)
• Humans
• Microbial Sensitivity Tests (methods)
• Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization (methods)